Infrared fluorescing optical signature agent method for real time change detection

ABSTRACT

A method of detecting changes in a scene comprising placing a fluorescent and/or phosphorescent compound in the scene and monitoring for elimination or change in position of the phosphorescent compound.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a divisional application of U.S. patentapplication Ser. No. 11/561,716 entitled “Infrared Fluorescing OpticalSignature Agent for Real Time Change Detection”, filed on Nov. 20, 2006,which application claims priority to and the benefit of the filing ofU.S. Provisional Patent Application Ser. No. 60/739,880, entitled“Infrared Fluorescing Optical Signature Agent for Real Time ChangeDetection”, filed on Nov. 22, 2005, and the specifications and claimsthereof are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable.

COPYRIGHTED MATERIAL

Not Applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

The present invention relates to unobtrusive methods and apparatuses fordetecting changes in a scene.

2. Description of Related Art

Security, surveillance, and defense systems use imaging sensors tomonitor unattended areas for evidence of unauthorized access, theft,tampering, and placement of bombs or other undesirable devices. It ismost desirable to have such a surveillance system be capable ofidentifying threats without man-in-the-loop monitoring.

Current systems to detect changes in imagery employ storage of theprevious images. The new data is then compared to the stored data usingan intensive processing system. The two sets of imagery are digitized,and loaded into memory. Multiple frames are stitched together into asuper-frame of data. The algorithm then looks for recognizable featuresin the scenery. These features are used as anchor points to register thetwo sets of data properly so as to reduce the rate of false alarms.Then, each pixel is subtracted from the corresponding, re-registeredpixel in the older data set.

The present invention is of a material and method of use thatdrastically reduces the amount of computation needed to determine scenechanges. One application for the present invention is in the monitoringof roadside guardrails and debris piles in Iraq, where ImprovisedExplosive Devices (IEDs) are being placed. A second potential use forthe material of the invention is as an optical marker tag on vehiclessuspected of containing car-bombs. Classical architectures for thisrequire extensive processing power and time to reduce the data. Theeffectiveness of these systems will be greatly enhanced by the abilityto identify specific areas of the imagery where something has changedrecently.

BRIEF SUMMARY OF THE INVENTION

The present invention is of a method of detecting changes in a scene,comprising: placing a fluorescent and/or phosphorescent compound in thescene; and monitoring for elimination or change in position of thephosphorescent compound. In the preferred embodiment, placing comprisesplacing a compound that is fluorescent and/or phosphorescent in infraredfrequencies, preferably one that is substantially not fluorescent orphosphorescent in visible light frequencies. The monitoring step canoccur by aircraft or satellite, and the scene can be illuminated withlaser light. Preferred inorganic compounds are erbium-doped InGaN,GaN/ZnSe, AlGaAs, AlGaN, silica nanoparticles with zinc nanocores, andzinc sulfide. Preferred organic compounds are4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran,5,12-Dihydro-5,12-dimethylquino[2,3-b]acridine-7,14-dione, Coumarinderivatives, poly(1-vinylnaphthalene, poly(2-vinylnaphthalene, andpolyaniline. One can additionally place an organic binding receptormaterial.

The invention is also of a liquid fluorescent and/or phosphorescentmaterial comprising: one or more compounds that are fluorescent and/orphosphorescent in infrared frequencies and substantially not fluorescentand/or phosphorescent in visible light frequencies; and a carrier.Preferred inorganic compounds are erbium-doped InGaN, GaN/ZnSe, AlGaAs,AlGaN, silica nanoparticles with zinc nanocores, and zinc sulfide.Preferred organic compounds are4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran,5,12-Dihydro-5,12-dimethylquino[2,3-b]acridine-7,14-dione, Coumarinderivatives, poly(1-vinylnaphthalene, poly(2-vinylnaphthalene, andpolyaniline. An organic binding receptor material can be included,preferably comprising one or more of activated telomerase polymers,biological entities, and bio-functionalized emissive infrared bandgapcompounds, most preferably including poly(phenylene vinylene). Thecarrier preferably comprises water and a carrier material, mostpreferably ethyl alcohol, methyl alcohol, isopropyl alcohol, ammonia, oralkyl dispersants.

Objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, and in part will become apparent tothose skilled in the art upon examination of the following, or may belearned by practice of the invention. The objects and advantages of theinvention may be realized and attained by means of the instrumentalitiesand combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Not Applicable.

DETAILED DESCRIPTION OF THE INVENTION

The Optical Signature Agent of the present invention is preferably aviscous coating that can be sprayed over an area to be monitored. Theagent preferably comprises an infrared fluorescing polymer material in alow-cost carrier such as SolGel. The agent preferably has a uniqueoptical phosphor-luminescence, with a strong signature that can beobserved by the camera or sensor system. The material will absorboptical energy, either solar or from an illuminator device, and re-emitthis energy with the specified signature. The signature can bemulti-spectral, or hyperspectral if required for anti-spoofing reasons.

Since the agent is deployed over a large area, the emission will berelatively uniform throughout the region being monitored. Any articlesintroduced into the area, items moved, or removed since the agent wasbroadcast will immediately be apparent in the imagery. In the example ofthe IEDs in Iraq, the optical agent can be sprayed from a helicopter incleared areas. Periodic flights over this area with the IR imagingsystem, tuned to match the spectral signature of the agent willimmediately identify areas where new items have been introduced or itemshave been moved. One such imaging system being developed by the Army isthe Lightweight Airborne Minefield Detection System (LAMD). This systemalso employs a wide field Infrared Laser which could energize theoptical agent for night flights. The LAMD system incorporatesgeo-location hardware to pinpoint the anomalies. Surveillance of acar-bomb will be considerably facilitated when the suspected vehicleradiates light that can be seen from a Police helicopter.

The broad area Optical Signature Agent is a passive application thatdoes not require any type of data storage or processing hardware toperform image subtraction. Real time display of analog imagery willplainly show discontinuities in the spectral signature anywhere therehas been a change in the scene since the last application of the agent.A comprehensive monitoring system, such as one comprising a centralserver or computer cluster, can identify the location of these anomaliesas the camera is swept over the scenery, and report these locations tomonitoring personnel or automated systems for further interrogation.

The preferred Optical Signature Agent preferably comprises anenvironmentally friendly paint with a phosphorescent compound similar toplastic children's toys that glow in the dark. However, the agent ispreferably clear and emits light in the infrared, making it invisible tothe human eye. This compound is used in concert with an infraredsurveillance camera system that can track any object that has beenmarked with the agent, or detect any previously sprayed areas wheresomething has been disturbed.

To reiterate, Improvised Explosive Devices (IEDs) are becoming anubiquitous problem. Note the following points regarding ways in which tolocate them: (1) An automated target recognition algorithm is unlikelyto work, since the devices are homemade and all look different; (2) Mostimaging sensor systems will not pick up IEDs, as they are oftenconcealed; (3) Chemical sensors may work well if they are directed to aspecific location to interrogate; (4) A sensor that detects changes inthe image can point out locations where something has been introduced,moved, or removed; (5) Classical surveillance sensors can only detectchange via an extensive digital image storage and processing technique,which is prone to a high false alarm rate, and requires considerabletime to complete; (6) What is required is a technique of detecting achange in the area of interest in real time, without the need to performsophisticated processing; and (7) Cleared and secured roadways, forexample, can be sprayed with the Optical Signature Agent of theinvention—then an airborne sensor can be flown ahead of troop movementsand search for anomalies, which can then be interrogated or avoided.

The preferred agent of the invention has a unique opticalphosphor-luminescence, with a strong signature that can be observed bythe camera, or sensor system. The material absorbs optical energy,either solar or from an illuminator device, and re-emits this energywith the specified signature. The signature can be multi-spectral, orhyper-spectral if required for anti-spoofing reasons. Since the agent isdeployed over a large area, the emission will be relatively uniformthrough out the region being monitored. Any articles introduced into thearea, items moved, or removed since the agent was broadcast willimmediately be apparent in the imagery. An airborne sensor can radiocoordinates of detected anomalies to following troops. An airborne laserilluminator can be employed to ensure that the agent will have energy toemit, even at night.

The compounds of the invention preferably exhibit the followingproperties, or at least a subset thereof: (1) Infrared (IR) emitters(radiative transition); (2) Fluorescence (strong—vib.) and/orphosphorescence (weak—vib.); (3) Low bulk cost; (4) Non-toxic liquiddispersive; (5) Aerosol (air compressive)—nitrogen carriers; (6) Bulkmass>air; and (7) Sensitivity for selective binding with IED compoundscontaining one or more of —NO₂, —NH₃, —ClO₄, —MnO₄, or —NO₃ linkages.

Potential low cost and environmentally friendly carrier systems fordispersing IR emitting compounds include: (1) EthylAlcohol/Aqueous—(10-50% EA)/(90-50% H₂O); (2) MethylAlcohol/Aqueous—(10-50% MA)/(90-50% H₂O); (3) IsopropylAlcohol/Aqueous—(10-50% IA)/(90-50% H₂O); (4) Ammonia/Aqueous—(10-20%NH₃)/(90-80% H₂O); and (5) Aqueous+alkyl (Na⁺, Mg²⁺, K⁺) dispersant.

The preferred IR emitting compounds emit in approximately the 2.5-4.5micron bandgap. Preferred emissive compounds specifically include bothinorganic and organic compounds. Inorganic compounds include: (1)InGaN/Erbium Doped; (2) GaN/ZnSe; (3) AlGaAs; (4) AlGaN; (5) SilicaNanoparticles/Zinc Nanocores; and (6) Zinc Sulfide. Organic Compoundsinclude (which can have primary fluorescence in the visible region): (1)DCM (4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran)dye (Sigma-Aldrich product 41, 049-7); (2) Especially when used as theemissive dopant in an Alq (tris(8-quinolinolato) aluminum) host layer,DMQA (5,12-Dihydro-5,12-dimethylquino[2,3-b]acridine-7,14-dione)(Sigma-Aldrich product 55, 758-7) provides improved operationalstability; (3) Coumarin derivatives, which have been employed as dopantsin PVK (polyvinyl carbazole) based multilayered EL (electroluminescent)devices; (4) Poly(1-vinylnaphthalene) (Sigma-Aldrich product 19, 193-0);(5) Poly(2-vinylnaphthalene) (Sigma-Aldrich product 46, 194-6); and (6)Polyaniline.

The preferred Organic Binding Receptor Materials (COTS) for attachmentto high explosive compounds include: (1) Activated telomerase polymers(ATP), such as Poly(phenylene vinylene) backbone polymerics; (2)Potential biological entities; and (3) Bio-functionalized emissive IRbandgap compounds.

Although the invention has been described in detail with particularreference to these preferred embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. Theentire disclosures of all references, applications, patents, andpublications cited above are hereby incorporated by reference.

What is claimed is:
 1. A method of detecting changes in a scene, themethod comprising: inspecting the scene to ensure that the scene is in adesired undisturbed state; coating at least a portion of the scene witha fluorescent and/or phosphorescent compound, the compound comprising aninorganic compound and an organic compound and having an emission inapproximately the 2.5 to 4.5 micron bandgap; and monitoring forlocations in the scene that lack the compound.
 2. The method of claim 1wherein coating at least a portion of the scene comprises coating with acompound that is fluorescent and/or phosphorescent in infraredfrequencies.
 3. The method of claim 2 wherein coating at least a portionof the scene comprises coating with a compound that is substantially notfluorescent or phosphorescent in visible light frequencies.
 4. Themethod of claim 1 wherein monitoring occurs by aircraft or satellite. 5.The method of claim 4 additionally comprising illuminating the scenewith laser light.
 6. The method of claim 1 wherein coating at least aportion of the scene comprises coating with an inorganic compoundselected from the group consisting of erbium-doped InGaN, GaN/ZnSe,AlGaAs, AlGaN, silica nanoparticles with zinc nanocores, and zincsulfide.
 7. The method of claim 1 wherein coating at least a portion ofthe scene comprises coating with an organic compound selected from thegroup consisting of4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran,5,12-Dihydro-5,12-dimethylquino[2,3-b]acridine-7,14-dione, Coumarinderivatives, poly(1-vinylnaphthalene, poly(2-vinylnaphthalene, andpolyaniline.
 8. The method of claim 1 wherein coating at least a portionof the scene comprises coating with an organic binding receptormaterial.
 9. The method of claim 1 wherein coating comprises sprayingfrom an airborne vehicle.
 10. The method of claim 9 wherein coatingcomprises spraying from a helicopter.
 11. The method of claim 1 whereinmonitoring comprises a user observing an image of the scene.
 12. Themethod of claim 1 wherein monitoring comprises a user observing thescene.
 13. A method of detecting changes in a scene, the methodcomprising: inspecting the scene to ensure that the scene is in adesired undisturbed state; coating at least a portion of the scene witha fluorescent and/or phosphorescent compound by spraying the compoundfrom an airborne vehicle, the compound comprising an inorganic compoundand an organic compound and having an emission in approximately the 2.5to 4.5 micron bandgap; and monitoring for locations in the scene thatlack the compound.
 14. The method of claim 13 wherein coating at least aportion of the scene comprises coating with a compound that isfluorescent and/or phosphorescent in infrared frequencies.
 15. Themethod of claim 14 wherein coating at least a portion of the scenecomprises coating with a compound that is substantially not fluorescentor phosphorescent in visible light frequencies.
 16. The method of claim13 wherein monitoring occurs by aircraft or satellite.
 17. The method ofclaim 16 additionally comprising illuminating the scene with laserlight.
 18. The method of claim 13 wherein the airborne vehicle is ahelicopter.